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OpenGL: How to render a glowing point/particle
Problem:
Rendering a point or particle that appears to glow in the dark is not as straight-forward as it sounds.
 
Solution:
Draw several points on top of each other, adjusting the PointSize and alpha component for each one.

my ($r,$g,$b) = @color;
glDisable(GL_COLOR_MATERIAL);
glDisable(GL_TEXTURE_2D);
glDisable(GL_LIGHTING);
glEnable(GL_POINT_SMOOTH);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
for my $n (1 .. 10) {
glPointSize(20/$n);
glColor($r,$g,$b,$n/10);
$size = $size / 2;
glBegin(GL_POINTS);
glVertex(4,4,4);
glEnd;
}

Remember that in a scene containing solid objects, the glowing points should be rendered AFTER the solid objects are done. Otherwise the background color will "shine through" solid objects that the points overlap.
 
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